This is a single inline TDS/purity meter which monitors any water purification system. It has an audible alert when the system requires service or maintenance. Features: Single line internal TDS monitor - great for most water purification systems which require TDS monitoring Includes a light and optional audible alarm that alerts the user when service is required and when the TDS reaches a pre-programmed set-point User-defined set points - any even number betwee 2 and 200. Specifications Range: 0-200 ppm (mg/L) Accuracy : +/- 2% Calibration: Factory calibrated Alert: Warning light, optional alarm Light color: Either red or yellow Light function: Either flashes or is steady Alarm: Beeps for 20 seconds, then goes silent Power Source: AC 110 volts / 220 volts ±2% Cable Length: 62.86 cm (24.75") Fittings: 1/4" standard, also available with 3/8" or 1/2" Max Water Presure: 200 psig Dimensions : 5" x 2.9" x 2.4" Weight : 12 oz